Just occataionally when i switch of the engine of the kit (cvh on 40's megajolted) it runs on a little rather than just coming to rest as you
would expect.
A freind of mine also has a stock A series that does it almost without fail.
Obvisouly at the moment it doesnt exactly cause me any problems but ive never really come up with a very good explanation for whats causing it.
Is it simply that the engine has suffient heat retained within it that once the spark has been removed it continues to run on compression ignition
breifly? Certainly in terms of the a series its fairly know for hot spots?
Clearly googling 'engine running on' doesnt return very concise results an i dont know any other name for the phenomina
Daniel
Not sure if it affects megajolt, but it could be feedback from the alternator. I know with megaquirt you have to put a diode in to stop this
happening.
Cheers
It may well be to do with how you have wired the alternator in and where the power is taken from for the EDDIS unit and the Megajolt unit. As above
the alternator may well be powering the eddis to produce a spark. untill all the fuel is taken from the carb.
Paul
Mine (CVH) would do that when the idle was set high.. This would make the plugs get too hot then deisel on switch off..
Have you the correct plugs??
Cheers
Dan
The A series was bad for it, I've seen a fair few with a factory fitted valve plumbed into the inlet manifold which needed an ignition live to
keep it shut. When you turned the ignition off the valve opened letting excess air in without fuel that helped to stop it.
I'm sure you could engineer something similar if need be, but better to cure the cause if you can.
quote:
Originally posted by dhutch
Just occataionally when i switch of the engine of the kit (cvh on 40's megajolted) it runs on a little rather than just coming to rest as you would expect.
A freind of mine also has a stock A series that does it almost without fail.
Obvisouly at the moment it doesnt exactly cause me any problems but ive never really come up with a very good explanation for whats causing it.
Is it simply that the engine has suffient heat retained within it that once the spark has been removed it continues to run on compression ignition breifly? Certainly in terms of the a series its fairly know for hot spots?
Clearly googling 'engine running on' doesnt return very concise results an i dont know any other name for the phenomina
Daniel
It will be worse if the idle speed is set high and the mixture isn't spot on. Another cause is if the igntion is too retarded but if that was the
case you would also expect the engine to run hot.
Unfortuneately twin DCOEs would make using an anti-dieseling valve difficult.
Using super unleaded should stop it.
ebay item 290378398193
its normally caused by a build up of carbon on something inside the cylinder. Normally a spark plug, valve coke or part of the head gasket. They get
red hot and when running and then when you kill the ignition it is hot enough to ignite the fuel. Running on carbs the fuel is sucked into the engine
when it needs it so will run on as long as something is there to ignite it.
As said above, you should remove and inspect the plugs, give them a clean with a wire brush (as long as they're not iridium tipped) and re fit
them. If this fails run on V Power! Not just super, it doesn't have the same cleaning properties as V Power. I'd also stick a fuel
treatment in the tank which should kick start the cleaning process. After a few long runs you should be noticing a good difference.
[Edited on 12/12/09 by Mark G]
i had it on mine. a diode on the battery light cured it.
easy way to test is disconnect the little small wire from the altenator. if it doesnt run on then you need a diode.
if it still runs on then you need to get the air fuel mix looked at.
Its called 'Dieseling' and is caused by hot elements inside the combustion chamber igniting the fuel air mixture after the spark is turned
off.
Causes can be carbon build up, rough edges in castings or sometimes because the wrong sparkplugs are fitted and the electrodes are glowing hot.
Fit throttle bodies! they don't suffer as fuel supply is shut off.
quote:
Fit throttle bodies! they don't suffer as fuel supply is shut off
Excellent info guys, thanks.
- I'll have to look into sticking a diode in it and see if that does the job.
Also, my freind says when ever the meastro does it, the engine is actaully running in reverse. If you raise the clutch on it while its doing it.
- Mine however the only time ive raised the clutch on it, was running the convential way.
Daniel
My pinto used to do it if the rad fan was running when you turned the ignition off. Needed a diode fitting really
yea, kind of as above....
There are 2 totally seperate reasons, both mentioned but nobody seems to have pointed out that fact!
The first, and most likely, is the mega ecu or edis module remaining powered via the charge warning light or another connection between permanent live
and the ignition controlled side of the car's wiring, and as said, a diode sorts that out, or a pull down resistor on the ignition fed circuit
live to the ecu.
Second, the engine might be dieselling, but that is rarely "proper running" more chuggling and stuttering after turning off until it finally
stops, and as said its usually due to too much heat somewhere in the combustion chamber.
The former is most likely though
Running on based on the "hot spot" theory (carbon deposits or wrong plugs) is normally rather poor - sounds a little "rattly" and random (as NS Dev says). If it sounds just like a delay between key-off and actually running ceasing, then there's something funny with your wiring..sticky relay maybe?
quote:
Originally posted by ss1turbo
Running on based on the "hot spot" theory (carbon deposits or wrong plugs) is normally rather poor - sounds a little "rattly" and random (as NS Dev says). If it sounds just like a delay between key-off and actually running ceasing, then there's something funny with your wiring..sticky relay maybe?